const regex = new RegExp('adm-list-table-cell.*?\\K[/ ]*(<span class="del".*?</span>)[/ ]*', 'g')
const str = `<td class="adm-list-table-cell align-right"><a href="iblock_element_edit.php?IBLOCK_ID=1&type=news&ID=2&lang=ru&find_section_section=-1&WF=Y" title="title">2</a></td><td class="adm-list-table-cell align-left adm-list-table-cell-last"> / / / / <span class="del">ALL</span> / / / / / / / / / / </td>`;
const subst = `$1`;
// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);
console.log('Substitution result: ', result);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions