要使用Apache POI库创建水印、设置文本字体或CTTextPath设置样式、移除双/单引号，可以按照以下步骤进行操作。

1. 创建水印：

import org.apache.poi.xwpf.usermodel.*;
import org.openxmlformats.schemas.wordprocessingml.x2006.main.CTSdtBlock;

public void createWatermark(XWPFDocument document, String watermarkText) {
    XWPFHeader header = document.createHeader(HeaderFooterType.DEFAULT);
    XWPFParagraph paragraph = header.getParagraphArray(0);
    if (paragraph == null) {
        paragraph = header.createParagraph();
    }
    XWPFRun run = paragraph.createRun();
    CTSdtBlock sdtBlock = run.getCTR().addNewSdt();
    CTSdtContentBlock sdtContent = sdtBlock.addNewSdtContent();
    XWPFParagraph watermarkParagraph = sdtContent.addNewP();
    watermarkParagraph.setAlignment(ParagraphAlignment.CENTER);
    XWPFRun watermarkRun = watermarkParagraph.createRun();
    watermarkRun.setText(watermarkText);
    watermarkRun.setFontSize(72);
    watermarkRun.setColor("A9A9A9");
    watermarkRun.setItalic(true);
}

2. 设置文本字体：

import org.apache.poi.xwpf.usermodel.*;

public void setFont(XWPFParagraph paragraph, String text, String fontName, int fontSize, boolean bold, boolean italic) {
    XWPFRun run = paragraph.createRun();
    run.setText(text);
    run.setFontSize(fontSize);
    run.setBold(bold);
    run.setItalic(italic);
    run.setFontFamily(fontName);
}

3. CTTextPath设置样式：

import org.apache.poi.xwpf.usermodel.*;

public void setCTTextPathStyle(XWPFParagraph paragraph, String text, int fontSize, String fontFamily, boolean bold, boolean italic) {
    CTP ctp = paragraph.getCTP();
    CTR ctr = ctp.addNewR();
    CTTextPath textPath = ctr.addNewPict().addNewSpPr().addNewTxWarp().addNewWarp();
    textPath.setWarp(STTextWarp.NONE);
    textPath.setPath(STPath.TEXT);
    textPath.setFitShape(STTrueFalse.T);
    textPath.setString(text);
    
    CTFont font = CTFont.Factory.newInstance();
    font.setSize(fontSize * 2);
    font.setBold(bold);
    font.setItalic(italic);
    font.setFamily(fontFamily);
    
    CTRPr ctrPr = ctr.addNewRPr();
    ctrPr.setRFont(font);
}

4. 移除双/单引号：

import org.apache.poi.xwpf.usermodel.*;

public void removeQuotes(XWPFDocument document) {
    for (XWPFParagraph paragraph : document.getParagraphs()) {
        for (XWPFRun run : paragraph.getRuns()) {
            String text = run.getText(0);
            if (text != null) {
                text = text.replaceAll("['\"]", ""); // 移除双/单引号
                run.setText(text, 0);
            }
        }
    }
}

使用上述代码示例，你可以在Apache POI库中创建水印、设置文本字体、CTTextPath样式以及移除双/单引号。记得在项目中添加Apache POI库的依赖。